The present invention relates to guide plates for use with internal combustion engines which include overhead valves, and a related method of assembly.
Many internal combustion engines include overhead valves that regulate the intake of fuel and air into one or more combustion chambers, as well as exhaust out of the chambers. Pushrod guide plates are usually employed with overhead valves to align a rocker arm with a tip of a valve, both in longitude and latitude, that is, the plate squares and positions properly (from left to right) the rocker arm relative to the tip of the valve.
Guide plates typically are positioned between the rocker arms and the bosses atop the cylinder head of the engine. The plates generally include two holes for mounting the guide plate to the cylinder head with bolts, and two slots, one of which is dedicated to guiding an intake pushrod, the other of which is dedicated to guiding an exhaust pushrod.
Most guide plates are mass-produced using conventional manufacturing techniques, such as stamping. Mass-produced plates are usually constructed from a single piece of rigid material.
A problem with conventional guide plates is that although they are usually well-manufactured, slight deformations that occur during stamping can make the plates incompatible with and unacceptable for high performance factory or aftermarket cylinder heads. Additionally, when installing conventional guide plates on highly specialized or high performance engines, which include intake cylinder ports and/or exhaust ports that have been relocated, the pushrods usually fail to align with those conventional plates.
A proposed solution to this problem is disclosed in U.S. Pat. No. 5,044,329 to Jamora, which shoes a two-part guide plate, where one plate includes a tab and the other plate includes a complimentary slot. The two plates can be moved, tab in slot, until a desired configuration is achieved, after which the plates can be welded together. Although this construction offers a partial solution, it also has its shortcomings. For example, if the pieces are welded, there is no way to correct any misalignment that may have occurred while the pieces were being welded—short of cutting and re-welding the pieces. Further, if the guide plates are removed and the pushrod position is altered, the welded guide plate parts must be cut and welded again to accommodate the new position. Finally, in some cases, the welding of the plates causes slight warping of the plates, which can alter alignment of components.